Predictive hypotension algorithm was not superior to treating at MAP 73 mmHg

Design

Two-centre, open-label, parallel-group randomised trial

Population

100 adults having major noncardiac surgery with invasive arterial monitoring

Primary outcome

Time-weighted average hypotension (MAP <65 mmHg)

Effect

Median 0.07 vs 0.16 mmHg (P = 0.119); no difference in noradrenaline, stay or 30-day mortality

This two-centre, open-label randomised trial, published in Anesthesiology on 29 September, allocated 100 adults having major noncardiac surgery with an arterial line to Hypotension Prediction Index-guided care (treat when the index reached 85) or a proactive threshold (treat when mean arterial pressure fell to 73 mmHg). Both groups used the same treatment protocol.

Time-weighted average hypotension below 65 mmHg was 0.07 mmHg with the index and 0.16 mmHg with the threshold (P = 0.12). Area under the threshold, hypertension burden, noradrenaline dose, hospital stay and 30-day mortality did not differ significantly.

Earlier trials suggesting the index reduced hypotension compared it with treating at 65 mmHg. This trial tests the idea that much of the benefit comes simply from acting earlier. It was small and not designed to show equivalence, so it does not prove the two are the same. But for most departments, particularly where the proprietary monitoring is not available or affordable, a higher treatment trigger is a reasonable, low-cost strategy to consider.

• Consider treating at a mean arterial pressure of about 73 mmHg rather than waiting for 65.
• Where predictive monitoring is unavailable, a higher trigger may achieve much of its effect.
• Keep the same vasopressor and fluid protocol whatever the trigger.
• Watch for over-treatment; hypertension burden was similar in both groups here.

Why it matters

The benefit credited to an expensive algorithm may mostly come from treating earlier.

Don't overread it

A 100-patient superiority trial; it shows no demonstrated difference, not that the strategies are equivalent.

The statistics, in plain English

A P value of 0.12 means the difference could plausibly be chance; the trial was too small to exclude a modest advantage for the index. No superiority is not the same as proven equivalence.

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